This investigation will use the Gunn rat as an animal model for the study of the perturbing effects of unconjugated bilirubin on the development of the neonatal brain. The work will focus on selected aspects of cerebellar protein synthesis, levels of GABA, GABA-T, and GAD and the morphogenetic perturbations in the cerebellum elicited by brain bilirubin. The interaction of bilirubin with enzymes and nucleic acids will be studied. The effects of bilirubin on the electrophysiology of kernicteric rat brain will be explored.